The present disclosure relates generally to communication systems, and more particularly, to user equipment mobility during Internet Protocol (IP) multimedia subsystem (IMS) calls.
Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
Communication services may be provided by multiple competing network operators within a geographical area. In an aspect, as radio access technologies deployed by network operators have become more similar, there is some degree of redundancy in deployment of network hardware. One proposal to reduce hardware redundancy and more efficiently deploy hardware is the concept of a neutral hosted network (NHN). A NHN may be a shared network that allows one or more network operators to offload traffic from subscribers onto the NHN.
Network operators, however, also seek to obtain a competitive advantage over competitors by providing high quality connectivity, especially for various priority services such as voice and video calls. In some cases, a NHN may be able to provide such services, but may be unreliable for providing the quality desired by the network operator responsible for the subscribers. Accordingly, there is a desire for network operators to maintain control over priority calls while allowing subscribers to offload traffic to a NHN or other network.